Soundboard Clamping for Downbearing

[Farrell]

"but I wonder about the permanent damage from over drying. What's your source on that?"

I looked, looked and looked, but could not find it. Somewhere I read, and I think it may have been you that posted a link to a 1923 (or so) study on the strength of sitka spruce for airplane use (maybe it was someone else). A large part of that paper reported on how different drying methods affect wood strength. I'm quite sure it was in there that it said that if you oven dry the wood to zero MC, you will destroy it's further use for MC - I think I just assumed that it would affect its other characteristics also.

The other post indicated "as low as possible" - that would be zero MC. I suppose in practice someone drying a panel "as low as possible" means more like "pretty low" and perhaps not zero MC. But hey, I saw what I saw and read what I read. I take folks at their word......unless otherwise inclined.

Terry Farrell

  
----- Original Message ----- 
From: "Ron Nossaman" <RNossaman@cox.net>
To: "Pianotech" <pianotech@ptg.org>
Sent: Saturday, December 21, 2002 10:56 AM
Subject: Re: Soundboard Clamping for Downbearing


> 
> >".....and placing new crowned ones, drying the board and the ribs 
> >carefully to a MC as low as possible and then gluing and clamping them 
> >together."
> >
> >Drying the board as much as possible will permanently damage the wood. It 
> >is not difficult to dry the board WAY BEYOND that desired. Most soundboard 
> >designs call for a EMC of 4.5% to 6% for rib glue-up. I think the 
> >compression crowned boards will tend to the lower end of that range and 
> >the rib crowned boards will tend to the upper range.
> >
> >Terry Farrell
> 
> Terry,
> Yes, he shouldn't need to dry the panel below 4.5% (if that), but I wonder 
> about the permanent damage from over drying. What's your source on that? 
> I've heard this before, but haven't found any verifiable source to 
> substantiate it.
> 
> Ron N
> 
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